Schlumberger Technology Corporation

Jiaqi Yang

Sandip Bose

Smaine Zeroug

Bikash Kumar Sinha

Ting Lei

Tarek M Habashy

Ma Luo

Ram Sunder Kalyanaraman

A method for torsional wave logging in a borehole of a subterranean formation. The method includes obtaining a torsional wave measurement of the borehole, wherein the torsional wave measurement represents characteristics of a torsional wave propagating within a cylindrical layered structure associated with the borehole, wherein the cylindrical layered structure comprises the subterranean formation and a completion of the borehole, analyzing, by a computer processor, the torsional wave measurement to generate a quality measure of the completion, and displaying the quality measure of the completion.

Torsional wave logging

Apparatus and method for characterizing a barrier installed in a borehole traversing a formation including locating an acoustic tool with a receiver and a transmitter at a location in the borehole, activating the acoustic tool to form acoustic waveforms, wherein the receiver records the acoustic waveforms, and processing the waveforms to identify barrier parameters as a function of azimuth and depth along the borehole, wherein the waveforms comprise at least two of sonic signals, ultrasonic pulse-echo signals, and ultrasonic pitch-catch signals.

Acoustic multi-modality inversion for cement integrity analysis

Techniques involve obtaining acoustic data from an acoustic logging tool, where the acoustic data includes waves reflected from the casing, the annular fill material, the formation, and/or interfaces between any of the casing, the annular fill material, and the formation. A crude casing thickness, tool position (e.g., eccentering), mud sound velocity may be estimated using the acoustic data. Techniques also involve computing a model spectra and an estimated casing thickness using a forward model and based on a crude casing thickness, an initial mud acoustic impedance, and an initial annular acoustic impedance, estimating a specular signal using the model spectra and the acoustic data in a first time window, computing a calibrated model signal using the estimated specular signal and computed model spectra, computing a misfit of the computed calibrated model signal and acoustic data in a second time window comprising the initial time window, and computing a correction update to one or more of the estimated casing thickness an estimated apparent annular acoustic impedance and an estimated mud acoustic impedance, based on the misfit. Techniques involve iteratively estimating the model spectra and the Jacobian curve, computing the specular signal, computing the misfit, and computing the update until the update is below a threshold. Outputs may include one or more of a casing thickness, an apparent acoustic impedance of the annular fill material, and the acoustic impedance of mud.

Fast model based inversion of acoustic impedance of annulus behind casing

Techniques involve obtaining acoustic data from an acoustic logging tool, where the acoustic data includes waves reflected from the casing, the annular fill material, the formation, and/or interfaces between any of the casing, the annular fill material, and the formation. A crude casing thickness, tool position (e.g., eccentering), mud sound velocity may be estimated using the acoustic data. A specular reflection signal may also be estimated based on the acoustic data. A modeled waveform may be generated using the estimated specular reflection signal and one or more model parameters, such as an estimated crude casing thickness, an estimated tool position, an estimated sound velocity of mud between the acoustic logging tool and the casing, an estimated impedance of the annular fill material, and an estimated impedance of the mud. The modeled waveform may be calibrated in some embodiments. Furthermore, a casing thickness may be estimated by matching the modeled waveform with the corresponding measured acoustic data. The techniques may output one or more of a thickness of the casing, an apparent impedance of the annular fill material, and the impedance of mud.

Model based inversion of acoustic impedance of annulus behind casing

Embodiments of the disclosure may include systems and methods for estimating an acoustic property of an annulus in a cement evaluation system. In one embodiment, a casing arrival signal is acquired at acoustic receivers a cement evaluation tool. A spectral amplitude ratio is calculated based on the casing arrival signal. The spectral amplitude ratio is scanned to detect and identify discontinuities. If discontinuities are detected, the frequency at the discontinuity may be used to estimate a wavespeed of the annulus. If discontinuities are not detected, attenuation dispersions are calculated and estimated, and an estimated wavespeed and parameters are updated until the calculated and estimated attenuation dispersions match.

Method to estimate cement acoustic wave speeds from data acquired by a cased hole ultrasonic cement evaluation tool

Apparatus and methods are provided. An ultrasonic tool with an array of axially spaced receivers and a transmitter is located in a borehole and is activated. Ultrasonic waveform indications recorded by the receivers are processed and analyzed to determine the presence of non-dispersive headwave signatures. If a non-dispersive headwave signature is located, the presence of a solid such as cement in the annulus is confirmed, and one or more of the compressional and shear velocities of the cement can be determined. If only casing dispersive mode signatures are found, the annulus is determined to possibly contain no cement at the location of interest and additional processing is required.

Methods and apparatus for evaluating properties of cement utilizing ultrasonic signal testing

Apparatus and methods for characterizing the physical state of a barrier installed in a borehole traversing a formation including locating an ultrasonic tool with a plurality of spaced receivers and a transmitter at a location in the borehole, activating the ultrasonic tool to form ultrasonic waveforms, wherein the spaced receivers record the ultrasonic waveforms, aligning the transmitter and the spaced receivers, wherein the ultrasonic waveforms comprise propagated Lamb modes, processing the ultrasonic waveforms to obtain a first amplitude dispersion plot of attenuation as a function of frequency and first phase dispersion plot of phase velocity as a function of frequency, processing attenuation dispersions to identify discontinuities, and relating the discontinuities to barrier wavespeeds.

Cement acoustic properties from ultrasonic signal amplitude dispersions in cased wells

Systems and methods for identifying sanding in production wells using time-lapse sonic data. Formation anisotropy can be characterized in terms of shear moduli in a vertical wellbore, e.g., vertical shear moduli Cand Cin the wellbore axial planes and horizontal shear modulus Cin the wellbore cross-sectional plane. Changes in formation anisotropy between different times can provide qualitative indicators of the occurrence of sanding in the production well. Before production begins, the horizontal shear modulus Cis typically less than the vertical shear modulus Cor Cor both. At a subsequent time after sanding occurs, the horizontal shear modulus Cis typically greater than the vertical shear modulus Cor Cor both. By comparing the shear moduli of the vertical wellbore at different times, it is possible to identify the occurrence of sanding in the production well using time-lapse sonic data.

Growing community of inventors

Belmont, MA, United States of America

Jiaqi Yang